2 - Data Organization

Step 1 locate the necessary data 1 locate the

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Unformatted text preview: ry data STORE: Save new data so that they can be located: (i.e. filing system). MODIFY: Change existing data. • Step 2: Perform operations on the data that were located (i.e. processing system). DELETE: Delete existing data. All these operations should be done efficiently with an acceptable level of resource use. Efficiency is essential in data organization. BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo 13 BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo 14 Physical Data Storage Data Storage Data Organization Organization • Sequential Storage • Physical Storage Storage – Data must be stored sequentially (in the order which the data are stored). – how data is stored on storage devices – Example: Magnetic tape • Access Method • Direct (Random) Storage – the way data is accessed (stored or retrieved) way data is accessed (stored or retrieved) – Data can be stored in any sequence (sequentially or randomly). – Usually use pointers to locate a related field or record of data. – Example: Magnetic or Optical disk BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo 15 BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo 16 Data Access Methods Access Methods Physical Storage Comparison Physical Storage Comparison Storage Type Sequential Direct (Random) Cost Low Medium to high Access Speed Slow Immediate, fast Reliability Less sensitive to external factors factors Sensitive to external factors factors BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo • Sequential A...
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This document was uploaded on 03/04/2014 for the course COMM 335 at UBC.

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